Care to share a bit more details on what you are doing with the HyperVM server?
There are many different types/setups of firewalls and all have different throughput levels also.
Are you filtering traffic? trying to prevent DDOS? Rate Limiting?
Do you want a hardware or software solution?
If you can give us some more details on what the server is doing, what traffic levels you expect, and what you want to acheive i'm sure we can start recommending something for you...